The present application relates to a capacitance sensor and an information input apparatus which are capable of detecting a contact or proximate position of a finger in accordance with changes in capacitance.
In recent years, there has been widespread usage of electronic apparatuses that detect a position of a finger in accordance with changes in capacitance and control screen display and apparatus operation. This kind of capacitance sensors generally determine a contact or proximate position of a finger in a flat plane by detecting changes in capacitance of a plurality of electrodes arranged in the flat plane. For example, Japanese Patent Application Laid-open No. 59-119630 (p. 3, FIG. 5) (hereinafter, referred to as Patent Document 1) discloses a touch switch apparatus having an electrode structure with two triangular touch electrodes formed by dividing a rectangle into two parts along a diagonal line, the touch electrodes being arranged in a uniaxial direction so that oblique sides thereof are opposed to each other with a slight clearance therebetween. According to such an electrode structure, since an area of a finger overlapping each of the touch electrodes varies depending on a uniaxial position of the finger, it is possible to identify a contact position of the finger in accordance with rates of changes in capacitance of the touch electrodes. In addition, Japanese Patent Application Laid-open No. 59-121484 (p. 3, FIG. 5) (hereinafter, referred to as Patent Document 2) discloses a coordinate input apparatus including a plurality of rectangular touch electrodes arranged in a biaxial direction at predetermined intervals in a matrix of 4×4, to identify a biaxial contact position of a finger in accordance with rates of changes in capacitance of the touch electrodes.